1. Field of the Invention
The present invention relates to a device for stabilizing an output of a photosensor which is applicable to a position sensor, light quantity sensor, and other sensors.
2. Description of the Prior Art
A photosensor is generally implemented by a combination of a light-emitting element (e.g. light-emitting diode) and a light-receiving element (e.g. light-receiving diode or phototransistor). Specifically, a light-emitting diode emits light responsive to a current fed thereto, while a light-receiving diode receives the light from the light-emitting diode through a rotatable disk and a mask each of which is formed with a number of slots therethrough. The output of the light-receiving diode is variable depending upon the quantity of light incident thereto. In principle, the output of the light-receiving diode remains constant if the current flowing through the light-emitting diode is maintained constant. In practice, however, it undergoes substantial variations as the ambient temperature changes, even if the current applied to the light-emitting diode is constant. Where such a photosensor is used for any of various kinds of controls, the susceptivity to ambient temperature is apt to result in significant errors in operation and, thereby, makes it difficult to accomplish an accurate control.